In 1907, the United Railroads of San Francisco built the vast Elkton shops, which would become the heart of URR’s heavy repair and overhaul facilities. Elkton was located at Ocean and San Jose Avenues and was named after the Southern Pacific railroad station located adjacent to the new shop complex. From June 1920 to December 1933, a total of 257 cars were built there. These cars, known as California Comfort Cars, were numbered 266 to 305 and 778 to 994 and during most of this period, the cars were turned out at a rate of about two cars per month. Market Street Railway, which resulted from a reorganization of the URR in April 1921, was proud of their car building capability and each car had a decal on an inside bulkhead that read "This car is a San Francisco product built in the shops of the Market Street Railway Company". The cars were modeled after the 201 to 265 class cars built by American Car Co. in 1913, but the home built cars were of lighter construction. In reality only the car bodies were new. The electrical equipment and trucks were recycled from older cars as they were scrapped

The fourteen cars, which were built between Jun and Dec 1925, were numbered 2001 to 2014 and were painted Blue and Gold to commemorate the Golden Jubilee of the State of California. These 14 cars were renumbered 299 to 305 and 837 to 843 in 1927.

After the last of these cars (994) was built, Elkton started a modification program to convert many of it’s cars to one man operation. Of the 257 cars, 131 were converted for one-man operation.

In May 1932, cars 284 and 285 were converted for one man operation on the South City line. Note that the rear door has been removed and folding air-operated doors have been installed in front. Two photos show car 285 as it emerged from Elkton. The third photo shows 285 in operation on the South City line.

Built new as a one man/two man car, 989 was photographed on June 26, 1933, as at came out of the Elkton Shops. The car is signed for the South City line.

In 1939, Market Street Railway adapted a new modernized paint scheme, with the addition of a "Zip Stripe" on the side of the car and a yellow roof. These views of 979, the first car to be so painted, were taken at the outer end of the #31 Balboa line. Some of the 900 series cars (963 to 988) had a higher gear ratio and more powerful motors (50hp) and were known as Balboa High Speed cars.

The Market Street Railway was sold to the City of San Francisco on September 29, 1944, and operation merged into the city owned Municipal Railway. Since there were duplicate numbers between Muni and Market Street cars in the 200 series, a number of former Market Street cars were renumbering into the 600 series. In this view we see 278 and 674 (ex 274) at Holy Cross cemetery on the #14 line. Holy Cross was a stop on the #40 San Mateo interurban, but on Sundays and other holidays the #14 line was extended from Daly City to serve the cemetery.

Market Street Ry 266 (the first car of this series) converted as a one man car at 24th Street car house.

Three views of cars in the low 800 series operating on the #11 line.

Car 835 configured as a two man car.

Car 849 operating along Ocean Avenue on the #12 line. This trackage is still in service as Muni’s K line and is served by LRVs.

After the merger with Muni, some of the Market Street cars found their way on former Muni lines. Here we see car 923 serving the Muni H line.

Balboa High Speed car 986 at the end of the #31 Balboa line. This was the last Market Street Ry line to be built and was placed in service on May 15, 1932.

Last car of the series, 994, operating on Mission Street.

These cars were all disposed of between 1945 and 1950. One car, 974, was purchased by the Bay Area Electric Railway Assn. in hopes of preserving it, but it unfortunately burned in the late 1950s. What is left of the car is at BAERA’s Western Railway Museum at Rio Vista Jct California. Another car, 798, was found being used as a shed a few years ago and is being restored to it’s original appearance for use as part of Municipal Railway’s historic trolley fleet.